1. Field of the Invention
The present invention relates to sleep detection warning devices and more particularly it pertains to a novel sleep alert warning system for waking a dozing driver.
2. Description of the Prior Art
Drivers of motor vehicles, especially truck drivers, often put in long grueling hours at the wheel of their vehicle. Because of the need or desire to reach a given destination at a given time it is not infrequent that drivers spend more time at the wheel than is reasonably prudent and safe or spend time driving fatigued long past when they should be asleep. It is not surprising then that motor vehicle accidents occur where the driver has dozed off at the wheel and where the vehicle has veered off the road. Accidents result not only in vehicle damage, property damage and severe injury or death of the driver, it can also result in the death or injury of other drivers or pedestrians in the area of the accident. According to the National Highway Traffic Safety Administration, there are about 100,000 police-reported crashes that are the direct result of driver fatigue each year. Accidents that occur when the driver falls asleep at the wheel often have a high percentage of fatality. NHTSA conservatively estimates fatigue-related crashes results in an estimated 1,550 deaths, 71,000 injuries and $12.5 billion in monetary losses each year. In Europe too the situation is very similar. The German Insurance Association—GDV (Gesamtverband der Deutschen Versicherungswirtschaft e.V.)—estimates that about 25 percent of all fatal accidents on German motorways are caused by tiredness.
A number of systems have been developed to attempt to alert the driver who is falling asleep. Volvo is introducing a complex system of cameras, sensors, processors and computer controls for their consumer based automobiles to alert when a driver has become fatigued by measuring the movement of the car. It apparently only works when the vehicle is traveling 60 KPH or more. The device works independent of the driver and depends on complex calculations without actually knowing the condition of the driver.
Eye and head movements have been associated with fatigue and some solutions have revolved around devices that utilize this information. In U.S. Pat. No. 6,107,922 to Bryuzgin issued Aug. 22, 2000 a self contained headset is described. The device monitors the position of a driver's lower jaw as an indicator of the driver's condition. The device is triggered when the drivers jaw moves downward triggering an alarm condition. The device relies on motion that could also occur during talking or head movement and isn't necessarily the first motion indicator of a tired driver. In U.S. Pat. No. 6,559,779 to Zoerb, a safety apparatus utilizing an eyeglass mounted light beam emitter and detector which will sound an alarm when a drowsy driver's eye closes and his eyelashes interrupt a focused light beam is described. The device requires accurate alignment and calibration and is affected by both exterior light sources and well as head movements and blink pattern.
It is known that as a driver fatigues, his grip on the steering wheel relaxes. Measurement of grip has been measured by devises which mount on the steering wheel and those that mount on the hand. In U.S. Pat. No. 6,218,947 to Sutherland issued Apr. 17, 2001 describes a sleep alarm mounted on the steering wheel comprising a pair of conductive elements that measure conductive capacitance between the two hands on the steering wheel. The difference is used to establish a baseline which when changed initiates an alarm.
In U.S. Pat. No. 6,016,103 to Leavitt issued Jan. 18, 2000 there are at least one pressure sensor on each of two gloves. The sensors can be positioned on any of the fingers (shown on the finger tips) or the palm of the hand. There is a remote communication means between the two gloves and an alarm is activated when grip pressure of both hands falls below a threshold level. The device requires the drivers grip to be relaxed on both hands to be triggered and the device has a preferred embodiment where grip pressure has to fall below a threshold for a given period of time. In U.S. Pat. No. 6,172,610 to Prus issued Jan. 9, 2001, there is described a contact means where there is a sensor mounted on a glove and a contact mounted on the steering wheel. As long as the glove and wheel sensors are in contact the alarm does not sound. Contact is measured by the drivers' skin resistance rather than pressure and has been considered unreliable since the ambient temperature differences effect perspiration and thus alter skin resistance readings. In U.S. Pat. No. 6,590,499 to D'Agosto, describes a steering wheel mounted alert system. It requires either a custom manufactured steering wheel or custom installation and requires the steering wheel to be firmly griped to be activated.
While it is clear that each of these devices fulfill a particular objective or requirement it is clear that each has particular limitations and in general are either extraordinarily complex or do not activate an alarm until the driver has already started to dose off. It would be useful if there was a sensor arrangement which sounded an alarm instantly when the driver starts to doze and not when he is asleep. It would be useful if the system were simple and operated with a minimum of complicated interactions.